Thermo-electric couple.



No. 764,175. -PATENTED JULY 5, 1904.v

' W. H. BRISTOL.

THERMO ELECTRIC, COUPLE. PPLIUATION FILED un. 1904. fno MODEL.' 2 SHEETS-sunny 1.

i muzwwmwy v?- No. 764,175. PATENTED JOLY 5, 1904.

W. E. BRISTOL.

THERMO ELECTRIC COUPLE.

APPLICATION FILED MAB.. 5. 1904.

N0 MODEL. 2 SHEETS-SHEET 2.

A Trop/vf Y.

Navegue.'

NIT-ED- STATES Patented July 5, i904.

PATENT Ormea.

THERMO-ELEc'rl-lc couPLE.

- SVEGIFIGATION formingpart of Letters Patent No. 764,175, dated July 5,- 190%. Application lle March 5, 1904. Serial No. 196,739. (No model.) n

To all `whom it may concern,.- Be it known that I, WILLIAM H. BRISTOL, a citizen of the United States of America, residing at Hoboken, in the county of Hudson andr SState of New Jersey, have 'invented certain new -and useful Improvements in Thermo- Electric Couples, specification.

My invention has reference t thermo-electicularly to elements adapted for use in instruments for measuring high temperatures-'- such, for instance, .as pyro'ineters of that class which determine temperatures from the measi ures of the strength of thermo-electric currents produced by heating the junction of two different metals or metal alloys.-

T he object of my invention is to render .the couple extremely sensitive to changes in temperature at the junction, While providing for an increased 'conductivity of the elements along their shanks for the purpose of 'reducing the resistance due to changes in tempera ture which occur along the length of the Shanks of the elements.

To this end my invention consists, essen' tiall'y, in a thermo-eleetriec'ouple having its elements reduced in cross-section at and adjoining their junction, the Shanks of the ele-I the line 4 4, Fig. 2. Fig. 5 isa plan or top,

view of a couple provided with means for cooling its outer or cold ends. Fig. 6 is a section on the line `6 6, Fig. V5. Fig. 7 isa plan View. showing a number of couples united to formathermic pile or battery. Fig. '8 is a perspective of amodiiied form for the pyrometer, and Fig. 9 is a like view of another modir tied form.

of which the following is aV tric couples and thermic batteries, and par' A Similar letters and numerals oi' reference' designate corresponding parts throughout the several views of the drawings.

Referring "at present to Fig. l of the drawings, the letter A designates a thermo-electric couple of which the Shanks a and l) are of an enlarged cross-section, so as to permit of the passage of the current generated at a low voli tage with comparatively small resistance, and c and d are the reduced portions of the element'sextending from said Shanks and united at l in ausual manner. These reduced portions of the elements'adjoining the junction render the couple incre sensitive to changes of temperature for an obvious reason, While the enlarged Shanks comparatively reduce the re- Sstance due to changes of temperature occurring along the length of the said elements, it

being understood that with the metals usually employed the resistance increases with. m crease of `temperature, and vice versa.

According to my invention I provide a couple which at its junction and parts adjoin- Aing thereto is renderedextremely sensitive to changes in temperature, while the conductivity of the elements is not influenced to any appreciable extent by changes in temperature.

In practice I prefer to reduce 4the outer or cold end's of the elements,.as at 2 2," for the purpose of Ycausin, 1; their temperature to be quickly influenced, so as to be easily maintained ata substantially constant temperature. The ends 2 of the elements are connected `by usual means, such as the couplings 3 3, with wires 1() and 11, leading to a galvanometer or other electrical indicating or recording or measuring instrument.

1n order to prevent too`rapid oxidation of the ends of the couples exposed to the lire and also to keep the elements insulated fromgeach other, 1 provide means as follows: The Shanks (t and b, as well as the junction and adjoining portions c and (l, are embedded in a refractory non-conducting material, Such as B, which surrounds said parts, and in practice this insulating and protecting material is reduced in thickness atand about the reduced portions c and d, adjoining the junction 1 substantially in proportion to the diferencezin cross-section between said latter parts and the Shanks a and I stances, as when the couple is immersed into a bath of molten metal, I prefer to provide, 1n

addition to the protective insulation, a sheathing C, oi' ironor like metal, or theJ protective insulation may be coated wlth graphite or other coating which will withstand the intense heats and serve as an additional protection for the insulating protective coating. The outer or -e'old ends of the couple may be maintained at substantially constant temperature by. usual jackets D, as shown in Fig. 5, through which a circulation of air, water, or steam is maintained by usual means. Of course the cold ends must be insulated from the jacket or the cooling iiuids, so as not to ground the elements. in the couples described the material of the elements is presumed to be of comparatively low price-such, for instance, as elements made.l respectively, of steel'and nickel, which will withstand the comparatively high temperature required for a large variety Ofcommercial uses-as, for instance, the tempering of steel in lead-baths.

. The construction as described enables me do provide at a low cost a thermo-electric couple adapted for most of the purposes for which heretofore the expensive platinum and platiuiun-alloys were employed.

. While I have herein described my invention embodied in one couple, it is of course to be understood that a series of 'couples could be lunited in the form of a thermic pile' or battery, as shown in Fig. 7.

In order to further increase the sensitivenessof the couple to changes in temperatureas, for instance, when embodied in a pyrometer-1 make use of the construction shown in Fig. 8 wherein the reduced-'portion of the ,couple is subdivided into a number of parts c' d oi' an aggregate area of cross-section the saine as that of the reduced portions c and d of the form shown in Fig. 1 or less than the area of cross-section of the Shanks a and b. It will be readily understood that the individual parts c d, being of less area than the parts o (Z in cross-section, will heat and cool more quickly, and consequently respond more promptly to changes in temperature. In this latter construction the couples at the reduced ends are in parallel, and consequently the eiectromotive force remains the same as that obtained by the construction. shown in Fig. i, While, however, if the aggregate area of cress-section of the reduced ends is greater than theI cross-section of the reduced ends in Fig. 1 less resistance is oii'er'ed at the reduced ends without affecting the sensitiveness of the instrumentin the same degree as it would affeet the construction shown in Fig. 1. In other words, the resistance of the vcou ple as a whole is decreased without material loss of sensitiveness, which could not be done with a single reduced end.

It is of course to be understood that a number Aoi" couples of the construction shown in Fig. -1 could be placed together .side by side to form a compound couple similar to that shown in Fig. 8, but having separate Shanks instead of one shank' common toall the reduced ends. The several couples would be united at their ends to common leads or conductors, and the effect would be' the same as that of the construction shown in Fig. 8. lIn Fig. 9 I have illustrated this construction. What Iclaim as ,new isl. A thermo-electric couple having its clements reduced in cross-section-at and near their junction for causing the couple to quickly respond to changes in temperature, substantially as described. l

' 2. A thermo-electric couple having its elements reduced in cross-section at and near #their junction-and having its Shanks of large conducting area, substantially as described. 3. A thermo-electric couple having its elementsreduced in cross-section at and near their junction and having their cold endsreduced in cross-section, substantially as dcscribed. V

4. A thermo-electric couple having its elements reduced in cross-section at and near their junction and having their cold ends reduced in cross-section, and means for cooling said cold ends, substantially as described.'

5. Ather'rno-electric couple having its elements reduced in cross-section at and near` their junction and having their,-cold. ends reduced in cross-section, andmeans for establishing a iuid circulation about the cold ends of the elements, substantially as described.

6. A thermo-electric couple having its elements reduced in cross-section at and near their junction and having its Shanks of large conducting area, combined with means for establishing a fluid circulation aboutthe cold ends oi' said elements, substantially as described.

7. A thermo-electric couple having its elements reduced in cross-section at and near their junction, and having its shanks of large area, combined with a protective insulating material, surrounding said elements, substantially as described'. f

.8. A thermo-electric couple having its elements reducedl incross-section at and near their junction, and having its Shanks of large area, combined with a-protective, insulating duced portions of the elements, substantially as described.

9. A thermoelectricA couple having its elements reduced in cross-section at and near their junction, and having its Shanks-of large area. combined with a protective insulating material surrounding said elements, and a sheathing forming a protection for said insulating material, substantially as described.

10. A thermo-electric couple having its elements reduced in cross-section at and near their junction, and having its shanks of large area, combined withl a protective insulating -material surrounding said elements, and re- "duced proportionately in thickness at the reduced portions of the elements, and a sheathing forming a protection for said insulating material, substantially as described.

l 11. A. thermo-electric couple having Shanks of comparatively large area and a plurality of joined ends of aggregate area of cross-section smaller than that of the area of cross-section ofthe Shanks, substantially as described.v

' 12. A thermo-electric couple having Shanks of comparatively large crosslsection subdivided into aipluralit'y of ends reduced at and near the junction, substantially as described. 13. A plurality of thermo-electric couples having their individual elements reduced in erossfsection at and near their junction for increasing their sensitiveness, and their cold ends respectively connected to common leads or cnductors, substantially as described.

. 14. Athermo-electric batterycomprising a plurality of couples having their'elements rewitnesses.

, WILLIAM H. BRiS'IOL. Witnesses:

' A. FABER' Dtr FAUR, Jr.,

RAENA H. YUDizKY. 

